Turbine machines provide energy for a wide range of uses. A turbine machine comprises at least a rotatable shaft and a plurality of blades. In some applications the plurality of blades comprise a fan. Examples of turbine machines include turbofan, turbojet, turboshaft, and turboprop engines; gas turbine engines; and wind turbines.
The energy produced by a turbine machine is generally either electrical or mechanical. As one example, turbine machines are used to provide propulsion to an aircraft. A typical turbine engine comprises a compressor, a combustor, a high-pressure turbine, and a low-pressure turbine.
In some turbine machines, particularly in turbine engines used for aircraft applications, it is desirable to attach a nose cone upstream from the plurality of blades of the turbine machine. Nose cones are sometimes referred to in the art as “intake cones,” “inlet cones,” “nose cowls,” or “spinners.” The nose cone can serve to reduce drag caused by the turbine machine, improve air flow to the plurality of blades, and avoid or limit damage potentially caused by impinging foreign objects. In supersonic aircraft, a nose cone is also advantageously used to slow the flow of air from supersonic flight speed to a subsonic speed before it enters the turbine machine.
As described below with reference to FIGS. 1A and 1B, the mounting of a nose cone to the turbine machine typically requires bolting the base of the nose cone to a support ring or retaining ring. The addition of a support or retaining ring and the use of a plurality of bolts to secure the nose cone increases the weight of the turbine machine, which is undesirable as it may negatively impact turbine efficiency. Further, positioning, bolting, and balancing the nose cone is a time- and labor-intensive process. Balancing the nose cone and turbine machine is necessary to address an uneven weight distribution, and typically involves attaching balance weights to the nose cone, fan, shaft, or other part of the turbine machine. However, small turbofan engines typically have limited space to accommodate balance weights and attachment features for nose cones.
FIG. 1 is a partial sectional view of a nose cone 10 connected to a fan rotor 12 of an inlet fan of a gas turbine engine in accordance with conventional methods as described in U.S. Patent Application Publication No. 2011/0236217. The illustrated nose cone 10 comprises a flange member 14 which tapers to a leading cone tip (not shown) and a region proximate the trailing edge 16 having a radial thickness greater than that of the remainder of the flange member 14. A support ring 18 having an axially-extending flange 20 is connected to the fan rotor 12. A bolt 22 engages the trailing edge 16 of nose cone 10 to an axial member 24 and support ring 18. One disadvantage of the configuration shown in FIG. 1 and similar nose cone mounting configurations used in the art is that the trailing edge 16 must be reinforced by increasing the thickness of the nose cone 10, which increases the weight of the nose cone 10 as well. Another disadvantage is the difficulty encountered when mounting the nose cone 10 to support ring 18, particularly when bolting the nose cone 10 to the support ring 18.
Another nose cone configuration is illustrated in FIG. 2. FIG. 2 is a partial sectional view of a nose cone 10 connected to an inlet fan of a gas turbine engine as described in U.S. Pat. No. 8,540,492. As illustrated in FIG. 2, a nose cone 10 comprises a flange member 14 which axially extends from leading cone tip (not shown) to a trailing edge 13. A radially thick mounting ring 26 is formed proximate the trailing edge 13. The mounting ring 26 defines a plurality of apertures 15 that are spaced apart about the circumference of the mounting ring 26. One or more of the apertures may include a recessed portion 17 for holding one or more balance weights 19. A fan rotor 12 is connected to retaining ring 28 having a mounting flange 30. A bolt 22 extends through an aperture 15 to connect nose cone 10 to the mounting flange 30. The bolt 22 also retains balance weight 19 within the recessed portion 17. As can be appreciated, the one or more balance weights 19 may be added or removed from recessed portions 17 without dismounting the nose cone 10 from the mounting flange 30.
As with FIG. 1, the nose cone 10 of FIG. 2 can be time- and labor-intensive to properly position, secure, and balance when installing. The many bolts 22 required around the circumference of the flange member 14, as well as the inclusion of retaining ring 28 in the assembly, can substantially increase the weight of the turbine machine.
It is therefore desired in the art to have improvements to nose cones and nose cone assemblies for turbine machines which reduce the overall weight of the turbine machine and simplify the process of coupling the nose cone to the turbine machine.